1. Technical Field
This invention relates to a door system for high temperature industrial environments, such as an access door for a boiler penthouse.
2. Description of the Prior Art
U.S. Pat. No. 4,574,973, issued Mar. 11, 1986, for DOOR SYSTEM FOR PRECIPITATORS OR THE LIKE, discloses a quick-acting gas sealing access door for industrial applications which operates in a temperature range up to about 400.degree. F. A normally flat metal door plate is equipped near its margin with a high temperature acid-resistant hollow core gasket which abuts a flat opposing frame plate when the door system is closed. A screw at the center of the door plate applies pressure inwardly against the door plate causing it to assume a concave configuration when closed to effect a gas-tight seal with the opposing frame plate. The patented access door is limited in its size and therefore is not completely suitable for applications where workers and/or large equipment must enter and leave an industrial device such as a boiler penthouse.